Effect of parallel electric fields on whistler mode waves in Jupiter's magnetosphere

Observation of auroral hiss at Jupiter by Voyager I has been suggested as being directly related to regions of parallel electric field and auroral particle precipitation. The effect of a parallel electric field on whistler mode propagation in Jupiter's magnetosphere has been studied. The dispersion relation for whistler mode waves in an isothermal one-component electron plasma in the presence of a parallel electric field has been used to study the growth of whistler mode waves propagating in the Jovian magnetosphere. The growth rates have been computed by using the observed plasma parameters at 5.6 Rj . The growth rate, which is found to be a maximum in the equatorial magnetosphere, is reduced to zero in the absence of the electrostatic field. This has lead us to conclude that, in the case of isothermal magnetosplasma, the growth rate is induced by the electrostatic field.         ARK: https://n2t.net/ark:/88439/y007466 Permalink: https://geophysicsjournal.com/article/16 &nbsp

Diagnostic accuracy of a three-gene Mycobacterium tuberculosis host response cartridge using fingerstick blood for childhood tuberculosis: a multicentre prospective study in low-income and middle-income countries

BACKGROUND: Childhood tuberculosis remains a major cause of morbidity and mortality in part due to missed diagnosis. Diagnostic methods with enhanced sensitivity using easy-to-obtain specimens are needed. We aimed to assess the diagnostic accuracy of the Cepheid Mycobacterium tuberculosis Host Response prototype cartridge (MTB-HR), a candidate test measuring a three-gene transcriptomic signature from fingerstick blood, in children with presumptive tuberculosis disease. METHODS: RaPaed-TB was a prospective diagnostic accuracy study conducted at four sites in African countries (Malawi, Mozambique, South Africa, and Tanzania) and one site in India. Children younger than 15 years with presumptive pulmonary or extrapulmonary tuberculosis were enrolled between Jan 21, 2019, and June 30, 2021. MTB-HR was performed at baseline and at 1 month in all children and was repeated at 3 months and 6 months in children on tuberculosis treatment. Accuracy was compared with tuberculosis status based on standardised microbiological, radiological, and clinical data. FINDINGS: 5313 potentially eligible children were screened, of whom 975 were eligible. 784 children had MTB-HR test results, of whom 639 had a diagnostic classification and were included in the analysis. MTB-HR differentiated children with culture-confirmed tuberculosis from those with unlikely tuberculosis with a sensitivity of 59·8% (95% CI 50·8–68·4). Using any microbiological confirmation (culture, Xpert MTB/RIF Ultra, or both), sensitivity was 41·6% (34·7–48·7), and using a composite clinical reference standard, sensitivity was 29·6% (25·4–34·2). Specificity for all three reference standards was 90·3% (95% CI 85·5–94·0). Performance was similar in different age groups and by malnutrition status. Among children living with HIV, accuracy against the strict reference standard tended to be lower (sensitivity 50·0%, 15·7–84·3) compared with those without HIV (61·0%, 51·6–69·9), although the difference did not reach statistical significance. Combining baseline MTB-HR result with one Ultra result identified 71·2% of children with microbiologically confirmed tuberculosis. INTERPRETATION: MTB-HR showed promising diagnostic accuracy for culture-confirmed tuberculosis in this large, geographically diverse, paediatric cohort and hard-to-diagnose subgroups. FUNDING: European and Developing Countries Clinical Trials Partnership, UK Medical Research Council, Swedish International Development Cooperation Agency, Bundesministerium für Bildung und Forschung; German Center for Infection Research (DZIF)

Anisotropy & Polarization of Hard Atmospheric X-rays

241-245The angular distribution of hard atmospheric X-rays is calculated on the assumption that they originate as Bremsstrahlung emission from energetic electrons. In contrast to previous calculations of this nature the relativistically correct Sauter formula [Sauter F, Ann Phys (France), 20 (1934)404] is used. The polarization of emissions greater than 10kev is calculated with the assumption that the precipitating electrons have monodirectional velocity distributions. The Bremsstrahlung generated by electrons spiralling in a uniformly magnetized atmosphere is found to be strongly polarized corresponding to small pitch angles of the precipitating electrons and the range of observational angles lying between 50ᵒ and 100ᵒ It is concluded that the precise measurement of photon flux and polarization can reveal the nature of energy spectrum of the precipitating electrons along with the pitch angle distribution in the incident electron beams

Calculation of Spectrum & Directivity of Hard X-rays from Solar Flares

56-62Energy and angular distributions of flare electrons have been studied as function of height using Monte-Carlo method. Initially, monoenergetic electron beams with vertical incidence directed towards photosphere are considered. Using these distributions, bremsstrahlung spectra and angular distributions are calculated. The total bremsstrahlung spectra have power law characteristics, with spectral indices increasing at high photon energies